Electric watch



Aug- 7, 1962 H. s. DETWILER f-:T AL 3,048,004

ELECTRIC WATCH Filed April 9, 1959 2 Sheets-Sheet l INVENTORS ATTORNEYS 2 Sheets-Sheet 2 ATTORNEYS H. S. DETWILER ETAL ELECTRIC WATCH' Aug. 7, 1962 Filed April 9. 1959 NM, Qw

nite taies caster, Pa., a corporation of Pennsylvania Filed Apr. 9, 1959, Ser. No. 805,312 7 Claims. (Cl. SI5- 28) This invention relates to a contact system for battery operated electric wrist Watches and more particularly relates to a contact system which produces a relatively constant contact pressure and which will maintain its initial adjustment.

The contact system of the present invention is intended to be used in an electric watch of the type having an oscillating coil in which the coil is carried on the balance wheel of the watch and energized on the forward swing of the balance wheel at 4the moment the coil passes over a pair of permanent magnets carried in the frame of the watch. This energization of the coil produces a magnetic ux within the coil which acts in a direction opposite to the permanent magnetic field and produces a thrust or kick against the coil which oscilla-tes the balance wheel in one direction. The motion of the balance wheel is customarily `arrested and returned by'a conventional hairspring, at which time the balance wheel oscillates inthe reverse direction and during this time the coil is not energized as it passes through Ithe permanent magnetic field.

Contact mechanisms have been devised in which a movable contact separate from thebalancewheel has been controlled and adjusted from two hubs mounted near the balance stati'. One such twohub system is disclosed in assignees copending application Serial No. 551,791, tiled December 8, 1955, now Patent No. v2,954,- 663, dated October 4, 1960. In this type of system, one

Pa., assignors to The Hamilton Watch Company, Lan- Patented Aug. 7, 1962 ent invention will become-more apparent upon reference to the following specification and claims and appended .drawings wherein: v

FIGURE 1 is a plan view showing the contact system of the present invention;

FIGURE 2 is a sectional view taken along the lines 2 2 of FIGURE 1; v

FIGURE 3 is a plan view of a novel anchor hub used in the present invention; and

FIGURE 4 is a front elevational view of FIGURE 3.

Referring now to FIGURE l, a balance wheel generally indicated at 10` is'suitably mounted for oscillation on a balance staff 12. A periodically energized coil 14 is mounted in a cut-out portion 16 in the balance wheel li) and is supported by a pair of beryllium-copper spring members l'whichare suitably attached to a skeletonized cross arm 2t) of the balance wheel 10 as by welding. The balance wheel carries one or more poising screws indicated at 21. Reference may be made toassignees end of a movable contact is frictionally carried by a collet on a first post and the end of a trip spring is mounted on a second post. The tip spring is utilized to control `the motion of the movable contact and is also frictionally carried by a collet on the second post. While this system has worked satisfactorily the arrangement of the l present invention presents certain material advantages. The reduction in the number of posts and parts involved provides a reduction in cost -and the nature of the systern provides a permanence of the original contact adjustment and setting. A relatively constant contact pressure is attained so as to eliminate hash in the coil current.

Accordingly, it is a primary object of the present invention to provide a contact system for a battery operated watch in which a movable spring contact maintains `a relatively constant contact pressure during its contact making period.

It is another object of the present4 invention to provide a novel means -or adjusting the contact period in a contact system for an electric watch.

It is still another object of the present invention to provide an improved means for prepositioning a movable spring contact in a contact system for an electric watch.

It is another object of the present invention to provide a novel means for insuring that a movablespring contact maintains electric contact with an oscillating electric contact carried by the coil of an electric watch.

It is still another object of the present invention to provide a novel means for returning a movable spring contact to its initial position out of the path of oscillation of an oscillating electrical contact after contact has been made.

TheseV and `further objects and advantages of the pres-` copending application Serial No. 781,809, tiled December 19, 1958, for the details relating to the mounting of the periodically energized coil 14.

A coil contact member 22 is attachedby any suitable means, such as screw 24, to a support member 26 which is cemented to the coil 14 and connected to one terminal thereof. Coil contact member 22 has anV arcuately curved portion 23 surrounding and insulated from the Vbalance staff 1 2 and carries an upstanding electrical contact 28 at the end thereof. 'Ihe axial position of upstanding electrical contact 28 is variable by virtue of a slot 311 in the end of coil contact member 22. (See FIG- URE 2.)

A collet 32 frictionally engages the balance stati 12 and serves as a.- support for the balance Wheel 10. A brass roller 34 is also carried on a ledge of collet 32 above the attachment of the balance wheel to the collet. This brass roller 34 carries a pin or cam member 36 called a trip jewel, the purpose of which will be described presently.

Referring now to FIGURES 1 and 2, an anchor hub arbor 38 is freelymounted for rotation between a contact bridge 40 and a lower bridge 42 by fa pair of olived bearings 44 and is thereby insulated from the frame `of the watch. Anchor hub arbor 38 carries an anchor hub indicated generally at `46. A contact spring 48 and 'a trip spring 5t) 'are securely `attached to anchor hub 46 as by welding. p

Reference is now made to FIGURESv 3 and 4 for the details of the anchor hub 46. Reference to these iigures discloses that anchor hub 46 consists of a base portion 52 and an upper portion 54. Upper portion 54 is slotted at 56'to receive one end'iof the electrical contact spring 48. Similarly, the base portion 52 is slotted at 58 to receive one end of trip spring 50. Slots 56 and 58 are positioned so that the radi-al distance to slot 56 is equal to the radial displacement of upstanding electrical contact 28 from balance stati 12 and the radial distance of slot 58 is made equal to the radial distance of trip jewel 36 from the balance staff 12.r Thispositioning of the slots 56 and 58 equal to the radial displacement of upstanding electrical contact 28 and trip jewel 36 is to insu-re that the anchor hub rotates through the same angular displacement `as the balance staff 12 during the time cycle of the malce and break contact.

Referring once again to FIGURES 1 'and 2, the electrical contact spring 4S and trip spring 50 areshown to be provided with looped portions 62 and 64 respectively. VLooped portion/62 enables the free end of electrical conleading edge of the trip jewel 36. Since the electrical contact spring 48 and the trip spring 50 are xedly attached to the anchor hub 46 such as by welding within slots 56 and 58, these members Will retain their initial position in a. positive manner. A precious metal contact 66 is carried on the free end of electrical contact spring 48 and engages the upstanding electrical contact 28 which also is preferably made from a precious metal such as gold.

A at tension spring 68 engages a flat surface 60 of anchor hub 46 to position the hub while permitting resilient motion away from the pre-established rest position. In this rest position, which is shown in FIGURE l, the end of the contact spring 48 is out of the path of movement of the upstanding contact 28. The other end of flat tension spring 68 is frictionally held within a kerf in a spring post 70 which extends through a contact bridge 72 which is suitably mounted above .the pillar plate or frame of lthe watch. The spring post 70 is electrically insulated from the contact bridge 72 by means of an insulating bushing 74. A compensating tension post 76 carrying an insulating bushing 78 bears against flat tension spring 68 at a bend 79 therein intermediate its ends. This post may be bent slightly to adjust the tension of spring 68 against hub 46. In addition to this, the spring y68 may be bent between post 76 and hub 46 in order to preposition the hub. A battery lead 80 is connected to the positive terminal of the battery 82 for the electric watch while the negative terminal of the battery is grounded to the watch frame. The second terminal of coil 1'4 is grounded to the balance wheel and statt and thence through collet 83, hairspring 85 and stud 87 to the watch frame.

The operation of the contact mechanism is as follows: Current flows from the `battery 82 to energize the coil 14 only rat the moment that it is in the magnetic eld and produces a magnetic thrust against the coil which, in conjunction with the reaction of the hairspring, produces an oscillating motion. At the position shown in FIGURE l, the balance wheel 10 is about to oscillate in a counterclockwise direction under the influence of the hairspr-ing. The forward face of the trip jewel 36 is in engagement with trip spring 50 and causes the anchor hub 46 to follow by rotating in the opposite direction. It will be noted that at this moment, the precious metal contact 66 of electrical spring contact 48 is not in engagement with the upstanding contact 28. However, because of its length, the offset nature of the attachment of electrical spring contact 48 to anchor hub 46 and the relative position of the anchor hub with respect to the upstanding contact 28, electrical spring contact 48 will make electrical contact with upstanding contact 28 by virtue of its relatively faster rotation. That is to say, the trip jewel 36 engages the trip spring 50 and causes` the anchor hub `46 to rotate vagainst the holding force of spring 68 thereby also causing movement of the contact spring 48 in the same direction.

The energization circuit comprises battery 82, battery lead 80, spring post 70, at tension spring 68, anchor hub 46, electrical spring contact 48, upstanding contact 28 of coil contact member 22, and electrical ground contact for the other terminal of coil 14, not shown, balance staff 12, collet 83, hairspring 85, stud 87, and the frame of the watch to the negative terminal of battery 82. This energization of coil 14 imparts the driving thrust `for balance wheel 10 and the duration of this thrust is determined by the adjustment loop 64 of trip spring 50 which in turn determines when trip spring 50 will slip past the forward face of trip jewel 36. As soon as trip spring 50 slips past the forward face of trip jewel 36, the only force acting on anchor hub 46 is that of the tension spring 68 which immediately returns the anchor hub to its initial predetermined position by virtue of the flat surface 60 on anchor hub 46 thereby breaking the electrical contact with a snap action. Adjustment loop 62 adjusts the wiping engagement of precious metal contact 66 with upstanding electrical contact 28.

As the balance wheel 10 rotates in a clockwise direction, the coil 14 will not be energized since the trailing face of trip jewel 36 will pass by the trip spring 50 which will yield to its motion. Precious metal contact 66 will be thus moved out of the path of upstanding contact 28. The balance wheel 10 will then begin its counterclockwise oscillation so that the forward face of the trip jewel 36 will again engage the trip spring 50 in the position shown in FIGURE l. j

The radial distance from the longitudinal axis of arbor 38 to slot 56 in which electrical spring contact 48 is lixedly contained is the same as the radial distance from the axis of balance staff 12 to upstanding electrical contact 28. Similarly, the radial distance to slot 58 which ixedly contains the end of trip spring 50 is equal to the radial distance from the axis of the balance staif 12 to the pin or cam member 36. Thus, the angular displacement of the balance staff will be equal to that of the anchor hub stalf, thereby insuring a relatively constant contact pressure.

It will be apparent from the foregoing that in addition to providing a contact systemhaving a relatively constant contact pressure during the contact making period, the present invention provides a novel adjusting means by loops 62 and 64 which insures reliability of adjustment. A single hub is used to control the motion of the electrical spring contact and trip spring thereby providing a reduction in the number of parts with a concomitant saving in production costs. Both the electrical contact spring 48 and the trip spring 50 are made relatively stif to insure that the breaking action will be substantially instantaneous and that the pre-positioning of the anchor hub 46 will be accurate.

The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiment is therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

What is claimed and desired to be secured by United States Letters Patent is:

l. In an electric watch operated by a battery, an oscillating balance stall, a coil carried by said balance staff for oscillation through a magnetic field, means :for periodically connecting said coil to said battery comprising a iirst electrical contact carried by said coil for oscillation therewith, a freely rotatable shaft mounted parallel to said balance staif, a hub mounted on said freely rotatable shaft for rotation therewith, a second electrical spring contact member tixedly mounted at one end to said hub and engageable with said iirst electrical contact, said hub being provided `with a at surface, a third electrical spring contact member constantly engaging said flat surface on said hub for positioning said second electrical spring contact member in an initial position out of the path of oscillation of said first electrical contact, cam means driven by said balance staff to cause said spring contact member to engage said iirst electrical contact as said first electrical contact oscillates in a first direction, said cam means being operable only during a portion of the oscillation of said first electrical contact in said irst direction, and said third electrical spring contact member being operable through engagement with said flat surface on said hub when said cam means is inoperable to return said second electrical spring contact member to said initial position.

2. In an electric watch operated by a battery, an oscillating balance staif, a coil carried by said balance staff for oscillation through a magnetic field, means for periodically connecting said coil to said battery comprising a tirst electrical contact carried by said coil for oscillation therewith, a freely rotatable shaft mounted parallel to said balance staff, a hub mounted on said freely rotatable shaft for rotation therewith, a second electrical spring contact member Xedly mounted at one end to said hub and engageable with said first electrical contact, said hub being provided with a fiat surface, a third electrical spring contact member, means lfor biasing a terminal portion of said third electrical spring contact member constantly into engagement with said fiat surface on said hub for positioning said second electrical spring contact member in an initial position out of the path of oscillation of said first electrical contact, cam means driven by said balance stai to cause said spring contact member to engage said first electrical contact as said first electrical contact oscillates in a first direction, said cam means being operable only during a portion of the oscillation of said first electrical contact in said iirst direction, and said third electrical spring contact member being operable through engagement with said flat surface on said hub when said cam means is inoperable to return said second electrical spring contact member to said initial position.

3. In an electric watch operated by a battery as set out in claim 2 wherein said means for biasing said third electrical spring contact member consists of a rotatable insulated post carrying the end of said third electrical spring contact member opposite said terminal portion and a fixed insulated post contacting said third electrical contact member intermediate its ends.

4. 'In an electr-ic watch, an oscillatable balance staf, a coil carried by said staff for oscillation through a magnetic field, means for periodically energizing said coil comprising a first electrical contact carried by said stati for oscillation therewith, a freely rotatable shaft mounted parallel to said balance staff, a hub mounted on said shaft, a second electrical spring'contact member fiXedly mounted at one end to said hub and engageable with said first electrical contact, spring means holding said hub in a rest position wherein said second electrical spring contact member is out of the path of oscillation of said first electrical contact, a cam arm carried by said hub and extending towards said balance statt, cam means carried by said balance stai for engagement with said cam arm when said balance staiit rotates in one direction to'move said second contact member into engagement with said first contact, said first contact being located a `distance from the axis of said balance staff substantially equal to the distance of said second spring contact member from the axis of said shaft, and said cam means being located a distance from said balance staff substantially equal to the distance of said cam arm from the axis of said shaft, whereby said second contact member engages said rst contact with substantially constant pressure during the period of contact.

5. An electric watch as `defined in claim 4 wherein said cam arm is provided with means for varying the length of time said cam means is in engagement with said cam arm when said balance wheel rotates in said one direction.

6. An electric Watch as defined in claim 5 wherein said last-mentioned means comprises a looped portion of said cam ar-m, whereby said cam arm may be longitudinally adjusted.

7. An electric watch as dened in claim 6 wherein said second electrical spring contact is looped intermediate its ends to permit adjustment of the position of the free end of said spring contact.

References Cited in the le of this patent UNITED STATES PATENTS 1,7 55,649 Holden Apr. 22, 1930 2,644,293 Black July 7, 1953 2,806,908 Van Horn et al Sept. 17, 1957 FOREIGN PATENTS 647,217 France July 24, 1928 

